Lean mass guide
Lean Body Mass Calculator in Kilograms
Calculate lean body mass in kilograms from metric height, body weight, sex, and optional body fat percentage.
Last updated: · Reviewed by the Lean Mass Calculator editorial team
Who this page is for
Metric users who want lean mass, fat mass, and protein targets in kg.
Start with the main lean mass calculator, then use the related tools below when you need body fat, FFMI, protein, or calorie context.
Interactive Calculator
Use this calculator to find your specific numbers before continuing with the guide.
Metric inputs to use
Enter body weight in kilograms and height in centimeters. The calculator converts nothing behind the scenes when both metric units are selected.
If you add body fat percentage, the direct calculation is weight in kg multiplied by the non-fat fraction.
Metric protein target
The homepage calculator uses 2.2 grams of protein per kilogram of lean body mass as a simple active-person target.
For a range by goal, use the protein intake calculator and enter your body fat percentage so the estimate is based on lean mass.
Worked example in kilograms
Take an 80 kg man at 178 cm. Using the Boer formula, LBM = 0.407 × 80 + 0.267 × 178 − 19.2 ≈ 60.9 kg, which is about 76% of body weight. Fat mass is the remaining 19.1 kg.
If instead you know your body fat is 18%, the direct calculation is simpler: LBM = 80 × (1 − 0.18) = 65.6 kg. The direct body-fat method is preferred whenever you have a reliable measurement.
Frequently asked questions
What is the kg formula for lean body mass?
With body fat percentage, LBM kg = body weight kg x (1 - body fat percentage / 100).
Can I convert lean mass kg to pounds?
Yes. Multiply lean mass in kilograms by 2.20462 to convert to pounds.
Is lean body mass in kg the same as muscle mass in kg?
No. Lean body mass in kg includes muscle plus bone, organs, and water, so it is larger than skeletal muscle mass. For a muscle-only estimate in kilograms, use the muscle mass calculator, which applies the Lee (2000) equation.
Sources & references
The estimates on this page use published lean body mass equations and clinical reference ranges. See the full reference charts on the lean body mass chart hub.
- Estimated lean body mass as an index for normalization of body fluid volumes — Boer P, American Journal of Physiology (PubMed) (1984)
- Percent Body Fat Norms and Reference Ranges — American Council on Exercise (ACE)
- Body Composition — Reference Information — National Institutes of Health (NCBI Bookshelf)